Timing of intrapartum transfusion among obstetric patients, stratified by admission and discharge haemoglobin, relative to anaesthesia care: A retrospective cohort study

BACKGROUND: We previously validated and implemented criteria for auditing anaesthesiologists with intraoperative transfusion based on low median blood loss of the surgical procedure or absence of anaemia before transfusion. However, obstetrical cases were excluded during implementation, as the peripartum blood management protocol does not include haemoglobin determinations, matching American College of Obstetricians and Gynaecologists recommendations. For non-obstetrical surgery, intraoperative transfusion is associated with an increased probability of postpartum transfusion. Because of the obstetrical transfusion approach, we hypothesized the opposite relationship between intrapartum and postpartum transfusion. METHODS: The retrospective cohort study included all 30 160 patients who delivered at the University of Iowa January 2013 through March 2025. RESULTS: Any RBC administration during anaesthesia care reduced the odds of later transfusion (odds ratio 0.14, 99% confidence interval (CI) 0.11%-0.18%). Single-unit RBC administration during anaesthesia reduced such odds (0.09, 99% CI 0.06%-0.11%), as did multiple-unit transfusion (0.18, 99% CI 0.13%-0.24%). McNemar tests had Bonferroni-adjusted p-values <0.0001. While antepartum anaemia (haemoglobin <11 g/dL) increased the probability of transfusion by 7.41% (standard error 0.43%) outside of anaesthesia care, the RBC transfusion decision during anaesthesia care was less influenced by anaemia, 1.52% (0.22%), p < 0.0001. Many (59%, 99% CI 50%-69%) RBC units started during anaesthesia care were administered to patients who were not anaemic (haemoglobin ≥11 g/dL) at admission. Most patients with single-unit RBC transfusion and blood loss <2500 mL had stable haemodynamics. CONCLUSIONS: Unlike several categories of non-obstetrical procedures, RBC transfusion during anaesthesia care for delivery was associated with a reduced probability of postpartum RBC transfusion. A reasonable approach for blood bank auditing of anaesthesiologists' obstetric RBC transfusion decision-making would be to review cases when RBC were administered, there was blood loss <2500 mL, no subsequent transfusion, and discharge haemoglobin ≥9 g/dL.